Blind stitch sewing is a method in which yarn or thread is sewn so as to emerge as a seam only on one side of the fabric while either submerging or not appearing at all on the other side. This type of sewing method is generally applied, for example, to fit a patched pocket or an outer pocket on a suit fabric since pocket formation may desirably be finished without emergence of a seam on the front the suit.
Conventionally, the blind stitch operation has been performed by effecting sewing motions of a curved needle reciprocatingly piercing the fabric along a slant or lateral direction instead of perpendicular thereto. According to this procedure, the inner pressure in the fabric must be carefully adjusted so as not to change position or be accelerated during the sewing motions. Although changes or sharp accelerations of fabric pressure should be avoided in blind stitch sewing, this is difficult due to the thickness of the fabric to be sewn. Examples of such blind stitch sewing include forming a patch pocket or a dart in a jacket suit. These operations do incur the difficulties noted above.
The need to adjust the fabric may be accomplished by regulating a distance between a presser rod and a fabric holding plate which is provided to hold the fabric. A means for accomplishing this by regulating a lowest stroke-endpoint of the reciprocating motion of the presser rod is described in another patent application by the same Applicant. In contrast, the present invention is intended to solve the same problem by adjusting the position of the fabric holding plate commensurate with changes of fabric thickness.